prameshj

We aren't sure of the rootcause of this, but browser privacy settings could cause it. Can you try one of the mitigations in https://firebase.google.com/docs/auth/web/third-party-storage-mitigation and see if it helps? Thanks!

> Check out this link: https://firebase.google.com/docs/auth/web/redirect-best-practices#update-authdomain > > This is a known issue and it results most likely from browser settings blocking third party cookies. When I allowed third party...

You need to attack either a safetyNet token or Recaptcha token from Android for Phone Auth - https://firebase.google.com/docs/auth/android/phone-auth#enable-app-verification. Similarly you need a suitable client identifier on iOS as described in...

The client identifier tokens are obtained via the client SDKs, so this is not really supported via rest APIs.

cc @renkelvin